Spin polarization in nonmagnetic materials has been traditionally ascribed to SOC in the presence of broken global inversion symmetry. The properties of the resulting non-trivial spin textures in momentum space have been widely studied for various classes of three-dimensional (3D) and two-dimensional (2D) non-magnetic crystalline systems lacking inversion symmetry.[1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]} This includes, in particular, crystal surfaces and interfaces, where SOC effects are enhanced by reduced dimensionality.[11]} Furthermore, for nonmagnetic materials, general rules have been established, which provide simple symmetry-based guidelines on the shape of spin textures in the Brillouin zone (BZ).[10]}
In recent years, the discovery of hidden spin polarization[13]}, [14]} and spin-layer locking[15]} in inversion-symmetric nonmagnetic semiconductors and semimetals has steered research interest towards centrosymmetric materials. This recent development has also shown that specific local-site inversion asymmetry combined with SOC could produce remarkable spin-polarization effects in the spin textures of nonmagnetic centrosymmetric crystals.[13]}, [14]}, [15]}
